3.3 Threats to Biodiversity Extinction and threats to biodiversity

Remember Extinct is FOREVER!!

Causes of Extinction Two major causes Natural Causes (Non-Human) Human Causes

Natural Causes (Non-Human) Volcanic Eruptions Drought Meteors Glaciers and ice age Competition and Predation

Human Causes (HIPPO) H-Habitat destruction and fragmentation I- Introduced species P-Pollution P-Practices of agriculture O-Over hunting Dodo Bird – Extinct

Habitat Destruction/ Fragmentation Degradation: reducing the quality of available habitat Ex. Logging, agriculture, sewage Fragmentation: splitting a single large, contiguous system into many disconnected areas Ex. Putting a road through a wilderness area, or building a dam across a river Loss: Disappearing of an entire habitat Ex. Paving natural area for building sites, converting prairies to farmland or residential subdivisions

Invasive Species (Alien, exotic, non-native) Organisms that are living in an environment outside of its normal range or natural environment Many are transported by accident Biocontrol: Species transported intentionally to control other “problem” species populations Characteristics: Fast growth/reproduction Live in wide range of environments Usually harmful to environment Outcompete native organisms for local food sources Leads to extinction of native organisms

Examples of Invasive Species Asian Carp Kudzu Rabbits Starlings Cane Toads

Kudzu “the vine that ate the South” and “The Green Menace”. Grow up to 1 foot in a day! Introduced from Japan as quick ground cover to prevent soil erosion

Asian Carp

Asian Carp Originally imported to clear algae from catfish ponds in the southern USA, Flooding allowed some carp to escape into the Mississippi River and its tributaries where they quickly became MANY carp Pose a strong threat to the Great Lakes Asian Carp Research

Rabbits “The introduction of a few rabbits could do little harm and might provide a touch of home, in addition to a spot of hunting.” -Thomas Austin in 1859 (Released 24 rabbits) 1950 ~ 600 million rabbits 1951 ~ 100 million Government Drugged Watering Hole

Starlings Today starlings are blamed for agricultural losses of up to $800 million annually in the United States, as well as being implicated in a number of deadly plane crashes. ~ 60 were released in New York’s Central Park in 1890.

Cane Toad

Cane Toad Good Example of biocontrol! In 1937 cane toads were released in Australia's sugar cane plantations to control insect populations By 1938 ~60,000 cane toads left sugar cane fields for more natural habitat (ate all majority of insect populations and outcompeted native amphibians for food) Can grow up to 15 inches and eat anything!

Pollution Toxins added to the environment lead to a loss or degradation of habitat.

Practices of Agriculture Farming causes habitat loss and reduces biodiversity because of… Monoculture: Farming of only one crop on a large scale Pesticides: Often lethal to many non-pest species Herbicides: Lethal to species other than the weeds

Over Hunting Collecting, and harvesting wild populations: unregulated, it can diminish local populations or even drive some to extinction Tasmanian tiger dodo North American sea mink Prairie buffalo Blue whale

Tragedy of Commons Tension between the common good and the needs of the individual and how they can be in conflict. If it belongs to all, we tend to exploit it

Tragedy of the commons (THE SEA) OVERFISHING IS HUGE PROBLEM TODAY! CURRENT RATE OF CATCH IS UNSUSTAINABLE

Characteristics of Vulnerable Species Organisms that are… Limited habitat Extremely specialized niche Low reproductive potential Require a large territory Migratory Valuable economically (hunted) Vulnerable to pollution Incompatible with civilization may be more likely to go extinct

Characteristics of Vulnerable Species Minimum viable population size The population needed for a species to survive in the wild Depends on genetic diversity, reproduction rate, mortality rate, growth rate, threats to habitat 500 is absolute for large carnivores

Rainforest Vulnerability Contain 50% of Earth’s known species Most species have specialized niches Humans disrupt environment for logging Changing one part of ecosystem alters the entire web of relationships Breakdown of rainforest likely lead to extinction of 10% worlds species in 25 years Regeneration rate is slow due to poor soil quality (rapid year round nutrient cycling depletes soil)

IUCN Red List Criteria

Red List Criteria IUCN (International Union for Conservation of Nature) Red list used to determine extinction risk Specific Aims: Provide system that can be applied consistently Improve evaluation of different factors which affect the risk of extinction

Factors used to determine list Population size: How many of this species exist? Reduction in population size: How fast is population decreasing? Numbers of mature individuals: These are past their reproductive years and may lead to further decline Geographic range and fragmentation: Wide range makes the species less likely to be threatened Fragmented habitat reduces interbreeding populations Quality of habitat: Degraded habitat supports fewer individuals

Categories Extinct (Ex) – No reasonable doubt that the last individual has died. Determined after exhaustive surveys of animals known range and expected habitats Endangered (E)- Survival is unlikely if causal factors continue operating. Drastically reduced populations and habitat

Categories Critically Endangered (CR) –considered to be facing an extremely high risk of extinction in the wild. Vulnerable (V) – Near endangered if causal factors continue. Numbers are abundant but are under threat from serious factors (overexploitation, habitat destruction)

Categories Near Threatened(NT) – Small world populations that are at risk. Unexpected threat could easily cause a critical decline (small geographic disturbance) Least Concern (LC) - Unknown (K) – Suspected to fit in one of the above categories but there is a lack of information

Red List Endangered Species Project